The present invention relates to an atomic absorption spectrophotometric method and apparatus for executing analytical measurement of various substance elements in a sample by adopting an atomic absorption of a light having a specific wavelength and more particularly to the atomic absorption spectrophotometer measuring an absorption spectra of the sample with high accuracy, by measuring plural specific absorption spectra which are generated by changing current of light source and a continuous absorption spectrum.
In a conventional atomic absorption spectrophotometer, the sample is vaporized by a burner or a furnace shaped like a tube, and the vaporized sample is passed through the light from the light source having a specific spectrum and a concentration thereof is detected by measuring the atomic absorption of the light. Such an atomic absorption spectrophotometer is suitable for measuring the concentration of traces of a metallic elements, especially heavy metallic elements.
As there are many other substances with target chemical elements in a frequency area of measuring spectra, the light absorption of the many substances caused by light scattering or molecular absorption etc., occurs so as to result in a measuring error. In order to attain correction of such error, in what is called background correction, absorption spectroscopy using a continuous spectrum, Zeeman atomic absorption spectroscopy and a background correction method using self-reversal of a spectrum line are generally employed.
U.S. Pat. No(s). 5,562,685 and 5,341,470 and Japanese publication "Bunkou Kenkyuu" (Vol. 35, No. 1, edited by Hidehiro Daidohji, 1986, pages 42 to 49) are cited as examples of such a method.
But the conventional technique has the following drawbacks. In the conventional method, a linear area of the detected absorbance of the spectrum is very short so as to narrow a measuring dynamic range of atomic absorption spectroscopy.